Police in Bolivia are blaming a gang for a spate of early morning murders in Bolivia where people have been strangled on minibuses while heading into work. Up to 69 people have been killed and dozens more were left for dead in El Alto, a working class city of one million people on an arid plateau above Bolivia's capital, La Paz. "This kind of assault came about because people, by necessity, take whatever transport they can get," said Felix Rocha, chief of Bolivia's police. Gang members would ride the buses posing as passengers, police said. After their victims had boarded, they were strangled with a rope or scarf and stripped of valuables that often amounted to little more than a mobile phone and the clothes on their backs. A 64-year-old man who said he survived an attack by the gang, recounted leaving his house at 4am on 5 February on his way to the bank where he collects his monthly pension. He said he boarded what he thought was a public transit minibus and as usual, his 25-cent fare was collected by "a cholita," or indigenous woman. "They had me sit in the front and suddenly I felt a scarf tightening around my neck. I fought back but they hit me in the ribs and face and I fell unconscious," said the man, who asked to be identified only by first name, Macario, because he fears for his safety. "I woke up later in a dumpster," Macario added. Gone was his mobile phone and the equivalent of £35 in the local currency. Police last week announced the arrest of eight alleged members of the gang, ranging in age from 30 to 45 and including a woman, Yuli Gutierrez Jimenez. Rocha said police seized four 14-seat minibuses used by the gang. Most of the killings occurred between 4am and 6am, when public transport is relatively scarce and only 400 police are on duty in the entire city, which is mostly unpaved and where many neighbourhoods lack running water and electricity. The gang is believed to have killed 69 people whose bodies have been found over the past 13 months, said Rocha, though prosecutor Santos Valencia said investigators are still trying to determine if the group was responsible for all those deaths. More than 70 people told police they had survived attacks after recognising gang members in local media reports, Rocha said. Other such gangs are known to exist, but the minibus gang seems to have been the best organised and most methodical, he added. Its alleged leader, Julio Edwin Valdez, 33, was arrested last week. Also captured was Galo Mamani, the bus's driver. Prosecutors said the two face murder charges but offered few other details. Valencia told reporters that police found wallets and the clothes of victims in the homes of those detained. Authorities did not say how they tracked down the alleged criminals. Rocha said police were investigating whether the group was also involved in the recent murders of several taxi drivers whose vehicles were stolen after the drivers were strangled.